MODELS OF MOLECULAR COMPOUNDS
Introduction: Molecular shape determines a compound’s boiling point, freezing/melting point,
viscosity and the nature of its reactions. The geometry of a small molecule can be predicted by
examining the central atom and identifying the number of atoms bonding to it and the number of
unshared electron pairs surrounding it. The shapes of molecules may be predicted using the
VESPR rule, which states that electron pairs around a central atom will position themselves to
allow for the maximum amount of space between them.
Purpose: Construct molecules and identify their molecular geometry. Predict the polarity of
molecules using their geometry and the types of bonds they contain.
Procedure: Construct ball-and-stick models of the following compounds. Complete the table.
Use the following code:
Black—carbon
Light blue—nitrogen
Yellow—hydrogen
Red—oxygen
Green—chlorine
Name
Hydrogen
(diatomic)
Formula
H2
Water
H2O
Methane
CH4
Ammonia
NH3
Hydrogen
chloride
HCl
Ethyne
C2H2
Dichloromethane
Carbon
dioxide
CH2Cl2
CO2
Methanol
CH2OH
Oxygen
(diatomic)
O2
Lewis
Structure
Structural
Representation
Shape
Molecular
Polarity
Name
Hydrogen
(diatomic)
Formula
H2
Water
H2O
Methane
CH4
Ammonia
NH3
Hydrogen
chloride
HCl
Ethyne
C 2 H2
Dichloromethane
Carbon
dioxide
CH2Cl2
CO2
Methanol
CH2OH
Oxygen
(diatomic)
O2
Lewis
Structure
Structural
Representation
Shape
Molecular
Polarity